The present invention relates to a wireless communication device and more particularly to an antenna assembly having a matching impedance network wherein a conductive planar element may function as both the primary radiating element of the antenna and the ground network of the device.
Techniques for end feeding a dipole antenna with an unbalanced 50 ohm feedline are known, including a xc2xc wave matching stub and a parallel LC circuit. Both the matching stub and parallel LC circuit act as impedance transformers between 50 ohms and the much higher impedance at the end of a dipole. The current invention does not contain a xc2xc-wave stub nor a parallel LC circuit.
Disclosed herein are wireless communication devices having efficient antenna structures including a matching impedance network. Wireless communication devices may include cellular telephones, PCS devices, PDA""s, etc. The matching network and an associated conductor panel define an antenna structure. In one embodiment, the conductor panel may be a ground plane of a printed wiring board of the wireless communication device. Additional advantages will be described with particular reference to the appended drawings.
Unique methods for edge- or end-feeding a conductor panel to create a broadband antenna are disclosed herein. A novel matching circuit structure provides a feed system for operatively coupling the wireless device""s signal generation circuitry to an end of the conductive plate resulting in primary radio frequency transmission from the conductor panel. The new feed system has a 50 ohm unbalanced input, and a single output connection point for the conducting plate.
As described herein, the conductor panel is caused to radiate RF signals by application of the matching network. The RF signal of the conductor panel is linearly polarized parallel to the longest dimension of the panel. The conductor panel may be generally rectangular, with a longest dimension of xc2xc wavelength minimum at the lowest frequency of operation. The dimension perpendicular to the longest dimension is not critical, and may vary from 0.005 wavelength to 0.25 wavelength. The conductor panel may desirably take the form of the common ground traces of a printed wiring board. The printed wiring board (PWB) of a cellphone or other wireless device provides a suitable conductor xe2x80x9cpanelxe2x80x9d.
Additionally, the matching network may be fabricated using standard printed circuit techniques and materials, making it inexpensive and suitable for mass production. The matching network may be disposed relative to another PWB, using commonly known fabrication techniques and practices. The matching network is relatively small in size and weight, and may be installed entirely within the interior of a cellphone or other wireless device (eliminating the necessity of an external antenna component and the potential for damage thereof).
As further discussed, the matching network may be connected between the 50 ohm antenna feed port of a cellphone or wireless device and the device""s ground plane to form an internal broadband antenna system having superior physical and operational characteristics.
An additional aspect of the present invention is to provide a broadband, compact, and lightweight matching network to interconnect low and high impedances is provided, having an operational bandwidth of 8-10% of the center frequency.
Yet another aspect of the present invention is the matching network to feed a conductor, such as a rectangular planar element, and cause it to operate as an efficient antenna over the bandwidth of the matching network.
Another aspect of the present invention provides that the dimensions of the antenna planar radiating conductor are much less critical than when using other feed techniques. Importantly, the antenna radiating conductor may be the common ground traces of a cellphone or other wireless device""s PWB. The matching network""s size is such that it can be installed within the interior of a typical cellphone or other wireless device.
Yet another aspect of the present invention provides a matching network which may be manufactured using ordinary printed circuit technology, to provide a low cost antenna system for cellphones and other wireless devices. Particular embodiments of the matching network may result in an antenna exhibiting front-to-back rejection, which may be useful for reducing power lost into the user""s body.
Still other objects and advantages of the present invention and methods of construction of the same will become readily apparent to those skilled in the art from the following detailed description, wherein only the preferred embodiments are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments and methods of construction, and its several details are capable of modification in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.